docs: def copyFeatures(self, featureSource):
          """ Copy the features from this source """
          if featureSource in self.sources:
              src, loc = self.sources[featureSource]
              if isinstance(src.features.text, str):
                  self.font.features.text = u""+src.features.text
              elif isinstance(src.features.text, unicode):
                  self.font.features.text = src.features.text